The reason for defensive lineman Art Jones being out of Thursday's season opener remains somewhat vague.
Ravens coach John Harbaugh shed a little light on Jones' illness on Tuesday, but said the team doesn't yet know how long it will keep him out.
"It's not life threatening or anything like that, but it's not football related," Harbaugh said. "We're just taking some tests on it to make sure he's OK. Until the tests come out the right way, he's not going to be able to play.
"It's something that I've been told now that they can't tell you how long it will be. It could be a week. It could be indefinitely. We don't think it's going to be the second (one). He's going to see a specialist here on Wednesday and he can explain exactly what it's about, to whatever extent he wants to."
Veteran Marcus Spears is expected to start in Jones' place. Spears has played in 119 career games with 89 starts. He started six of 15 games a year ago with Dallas.
"Marcus has been around, he's in good shape," Harbaugh said. "He's practiced well since he got over the hamstring. He really looks good and is ready to go."
Update: Jones tweeted twice, asking the public to respect his privacy in relation to his undisclosed illness.
In other injury news, tight end Ed Dickson expressed optimism about playing at Denver despite missing much of training camp with a partially torn hamstring.
He wouldn't say he's completely certain he'll play Thursday, however.
"I'm not 100 percent sure, but I feel 100 percent," Dickson said. "Physically, I feel 100 percent and personally, I feel like I can go every single day. I'm being smart with it. I'm going with the coaches, I'm going with the trainers. We're going day to day and we're going to see how we feel about it."
Barring a setback, Dickson anticipates he'll be able to play.
"You can say that," he said. "I'm very optimistic about it. When I first got hurt, you get down, you get down in the dumps and you're like, 'OK,' and you battle back. That's why I continue to do the same treatments and the same things. Even though I'm feeling better now, I still do the same things I've been doing these last two weeks, four weeks getting ready for this game.
"It's a long season, so it's not going to kill me to not play this game or anything like that because there's a long season ahead of us."